CN1842246B - Pad structure, printed circuit board and electronic device - Google Patents

Abstract

The present invention relates to a pad structure for soldering electronic components, a printed circuit board, and an electronic device, and aims to provide a pad structure, a printed circuit board, and an electronic device that can be soldered by supplying an appropriate amount of solder to leads and pads. The present invention is a welding pad (152) structure in which the connecting portion (132) of an electronic component (111) is welded, which is characterized in that the edge (162) of the bonding pad (152) is inclined relative to the end face of the connecting portion, and the bonding pad (152 ) is inclined parallel to the flow direction (A1-A2) of the molten solder.

Description

Pad structures, printed circuit boards and electronic devices

technical field

The invention relates to a pad structure, a printed circuit board and an electronic device, in particular to a pad structure for soldering electronic components, a printed circuit board and an electronic device. the

Background technique

Generally, the shape of a land portion where a lead of an IC or the like is soldered is a rectangle. In addition, solder reflow and solder forward flow are used as methods for soldering leads and lands of ICs and the like. the

Solder reflow is to print solder paste on the leads and pads in advance, and heat the leads and pads after mounting the electronic components, and the printed circuit board and electronic components are heated. At this time, solder reflow is used, because the amount of solder can be adjusted in advance, and even if the pitch of the pins is narrow, solder bridges can be prevented from occurring between the pins and the pads. However, since the printed circuit board needs to be heated, it is necessary to use a printed circuit board with high heat resistance. Therefore, the required cost is high. In addition, it takes a long time to apply solder paste. the

In contrast, solder flow is to solder pins and pads by bringing the printed circuit board on which electronic components are temporarily fixed into contact with molten solder. Since the solder flow is adopted, since it is not necessary to heat the printed circuit board, it is possible to use a printed circuit board with low heat resistance and reduce costs. However, the amount of supplied solder varies depending on the flow of solder and the positions of leads and pads. Therefore, when the pitch of the leads is narrow, if the amount of solder supplied is large, solder bridges will occur between the leads and the pads, and in places where the amount of solder supplied is small, the amount of solder will not be sufficient, resulting in the occurrence of lead and solder bridges. Poor contact of pad. Therefore, conventionally, solder flow cannot be applied to ICs with narrow pin pitches. the

In addition, a proposal has been made to increase the reliability of soldering in the case of narrow pitches by providing via holes while folding back the front ends of the leads (see Patent Document 1 - Japanese Unexamined Patent Publication No. 9-223769 ). the

For easy and inexpensive soldering, it is desirable to solder ICs with narrow lead pitches by soldering downstream. the

Contents of the invention

The present invention is made in view of the above-mentioned problems, and an object of the present invention is to provide a pad structure, a printed circuit board, and an electronic device capable of supplying and soldering an appropriate amount of solder to leads and pads. the

The present invention provides a pad structure for soldering a pad of a connection portion of an electronic component, a printed circuit board having a pad, and an electronic device. It is characterized in that the edge of the pad is inclined with respect to the end surface of the connection part, and the edge of the pad is inclined parallel to the flow direction of the molten solder. And the inclination is formed by the unevenness of the front end portion of the pad. the

Said reference signs are for reference only. The scope of technical solutions is not limited by this. the

According to the present invention, since the flow of solder supplied to the connection portion can be controlled by inclining the front end of the land, solder bridges can be prevented from occurring even if the distance between the connection portion and the land is narrow by adjusting the amount of solder supplied to the connection portion and the land. Or the welding is not complete, so that the welding effect is good. the

Description of drawings

Fig. 1 shows an exploded oblique view of an embodiment of the present invention. the

Figure 2 shows an installation view of an embodiment of the present invention. the

Fig. 3 is a perspective view showing main parts of an embodiment of the present invention. the

Fig. 4 shows a plan view of main parts of one embodiment of the present invention. the

FIG. 5 is a configuration diagram of main parts of an embodiment of the present invention. the

FIG. 6 is an explanatory view showing an operation of an embodiment of the present invention. the

FIG. 7 shows a plan view of a variant of an embodiment of the present invention. the

In the figure: 100-electronic device, 111-electronic component, 112-printed circuit board, 121-IC main body, 122-pin, 131-extension part, 132-connection part, 141-epoxy resin board, 143-protective film , 151-wiring part, 152-pad, 162-edge. the

Detailed ways

FIG. 1 shows an exploded perspective view of one embodiment of the present invention, and FIG. 2 shows an installation view of one embodiment of the present invention. the

In the electronic device 100 of this embodiment, the electronic component 111 is soldered to the printed circuit board 112 . the

Electronic Components 111

The electronic component 111 is constituted by a semiconductor integrated circuit, and pins 122 extend outward from the IC main body 121 . The IC main body 121 is formed by sealing an IC chip with resin. The pin 122 is connected with the IC chip through wires. the

The lead 122 is in the shape of a surface mount gull's wing, and is composed of an extension part 131 and a connection part 132 . the

The extension portion 131 extends from the IC main body 121 and has a shape bent toward the bottom surface of the IC main body 121 in the direction of the arrow Z2. A connecting portion 132 extends from a front end of the extension portion 131 . the

The connection portion 132 is bent parallel to the bottom surface of the IC main body 121 at the front end of the extension portion 131 . At this time, the connection portion 132 protrudes in the arrow Z2 direction slightly below the bottom surface of the IC main body 121 . The connecting portion 132 is soldered on the printed circuit board 112 . the

Printed Circuit Board 112

The printed circuit board 112 is formed by forming a wiring pattern 142 with copper foil or the like on an epoxy resin substrate 141 and almost entirely covered with a protective film 143 . the

The wiring pattern 142 is composed of a wiring portion 151 and a pad 152 . The wiring portion 151 is formed on the lower portion of the protective film 143 and is a pattern for wiring between the electronic components 111 . the

The pad 152 is a portion on the wiring pattern 142 from which the protective film 143 is removed. It is a portion to be soldered to the connection portion 132 of the pin 122 . the

Pad 152

3 shows a perspective view of the main parts of an embodiment of the present invention, FIG. 4 shows a top view of the main parts of an embodiment of the present invention, and FIG. 5 shows a configuration diagram of the main parts of an embodiment of the present invention. the

The inner peripheral side of the pad 152 , that is, the edge 161 on the IC main body 121 side slightly coincides with or is slightly located on the inner peripheral side of the IC main body 121 side of the connecting portion 132 of the lead 122 on the IC main body 121 side. In addition, the outer peripheral edge 162 of the pad 152 is located on the outer peripheral side of the front end portion of the connection portion 132 of the pin 122 and has an inclined shape. the

The outer peripheral edge 162 of the pad 152 forms an angle of θ=30 to 45 degrees with respect to the end surface of the connection portion 132 of the pin 122 . In addition, the width W of the pad 152 is approximately the same as or slightly larger than the width of the connecting portion 132 of the lead 122 . the

When solder flows from the direction of arrow X1 to the direction of arrow X2 on the edge 162 of the pad 152, the solder is guided to the direction of arrow Y1 according to its inclination, and the solder is supplied to the end surface of the connecting portion 132 of the pin 122, thereby, Incomplete soldering between the pin 122 and the pad 152 can be prevented. the

When solder flows from the direction of arrow X2 to the direction of arrow X1 on the edge 162 of the pad 152, the solder is guided to the direction of arrow Y2 in the direction of the front end according to its inclination, and the supply to the end surface of the connection part 132 of the lead 122 can be prevented. Excessive solder, thereby, can prevent solder bridging between adjacent pins 122 and pads 152. the

The operation thereof will be described below. the

FIG. 6 is an explanatory view showing an operation of an embodiment of the present invention. the

Here, the operation of soldering the electronic component 111 shown in FIGS. 1 and 2 to the printed circuit board 112 will be described. the

In this case, molten solder flows from the side in the direction of arrow A1 to the direction of arrow A2. At this time, the edges 162 of the pads 152 of the printed circuit board 112 are parallel in the directions A1 and A2. the

When the connecting portion 132 of the electronic component 111 and the pin 122 is aligned with the pad 152 to fix it, and when the molten solder flows from the side in the direction of the arrow A1 to the direction of the arrow A2, the solder is absorbed by the side of the IC main body 121 in the direction of the arrow A1. Blocked by the end face of the IC main body 121 on the side of the arrow A1 direction, the end face stagnates. In addition, since the solder is on the end surface of the IC body 121 in the direction of arrow A2, the supply of the solder is difficult, and similarly, the flow of the solder is stagnant. the

At this time, since the edge 162 of the pad 152 is formed parallel to the directions indicated by the arrows A1 and A2 of the flow direction of the solder, it acts on the side of the IC body 121 in the direction of the arrow A1 to guide the solder to the IC body 121. The arrows in the direction of the end surface of the B1 and B2 directions can prevent stagnation of the solder. In addition, it acts on the side of the arrow A2 direction of the IC body 121 to guide the solder to the directions C1 and C2 indicated by the arrows outside the IC body 121 , thereby preventing stagnation of the solder. the

As described above, since stagnation of the solder on the pad 152 can be prevented, the connection portion 132 of the pin 122 can be sufficiently soldered to the pad 152 . Therefore, it is possible to prevent solder bridges from being formed between the pins 122 and the pads 152 . Incomplete soldering of the pin 122 and the corresponding pad 152 can also be prevented. the

Modification

FIG. 7 shows a plan view of a variant of an embodiment of the present invention. the

In this embodiment, although the inclination is changed into a straight line, the solder can be supplied to or discharged from the connecting portion 132 side, but it is also possible to bend the edge 261 of the pad 152 into a convex shape as shown in FIG. The inclined portion 262 and the inclined portion 263 are provided. The supply and discharge of solder by the inclined portion 262 and the inclined portion 263 can prevent stagnation of the solder. In addition, by changing the length or angle of the inclined portion 262 and the inclined portion 263, the balance between solder supply and solder discharge can be adjusted. the

In addition, as shown in FIG. 7(B), the edge 361 of the pad 152 may be bent into a concave shape, and an inclined portion 362 and an inclined portion 363 may be provided. Like the inclined portion 262 and the inclined portion 263 , the solder is supplied and discharged by the inclined portion 362 and the inclined portion 363 , so that stagnation of the solder can be prevented. In addition, by changing the length or angle of the inclined portion 362 and the inclined portion 363, the balance between solder supply and solder discharge can be adjusted. the

Furthermore, as shown in FIG. 7(C), the edge 461 of the pad 152 may be bent into a convex shape and kept inclined. The supply and discharge of solder are performed by the inclination of the edge 461, and stagnation of the solder can be prevented. Alternatively, as shown in FIG. 7(D), the edge 561 of the pad 152 may be bent into a concave shape and kept inclined. The supply and discharge of solder are performed by the inclination of the edge 561, and stagnation of the solder can be prevented. the

other

In this embodiment, the electronic component 111 whose pins 122 are drawn out from four sides has been described, but the present invention is not limited thereto, and the same effect can be expected for an electronic component whose pins are drawn out from one side or two sides. the

In addition, the electronic components are not limited to semiconductor integrated circuits, and driven components such as chip resistors, chip capacitors, and chip inductors, and discrete components such as transistors also have the same effect. the

Claims (6)

1. pad structure, the connecting portion of welding electronic unit is characterized in that:

The edge of above-mentioned pad is with respect to the end slope of above-mentioned connecting portion, and the flow direction of the scolding tin of the edge of above-mentioned pad and fusing tilts abreast;

Use the scolding tin following current that pad and connecting portion are welded; And

The linearly inclination in the edge of pad, the inclination of this linearity is parallel with the scolding tin flow direction of scolding tin following current.

2. pad structure according to claim 1 is characterized in that:

By the edge that makes above-mentioned pad is the concavo-convex above-mentioned inclination that forms.

3. printed circuit board (PCB) is formed with the pad of the connecting portion of welding electronic unit, it is characterized in that:

The edge of above-mentioned pad is with respect to the end slope of above-mentioned connecting portion, and the flow direction of the scolding tin of the edge of above-mentioned pad and fusing tilts abreast;

Use the scolding tin following current that pad and connecting portion are welded; And

The linearly inclination in the edge of pad, the inclination of this linearity is parallel with the scolding tin flow direction of scolding tin following current.

4. printed circuit board (PCB) according to claim 3 is characterized in that:

By the edge that makes above-mentioned pad is the concavo-convex above-mentioned inclination that forms.

5. electronic installation, the connecting portion with electronic unit and this electronic unit is welded on the printed circuit board (PCB) on the pad, it is characterized in that:

The edge of the above-mentioned pad of above-mentioned printed circuit board (PCB) is with respect to the end slope of above-mentioned connecting portion, and the flow direction of the scolding tin of the edge of above-mentioned pad and fusing tilts abreast;

Use the scolding tin following current that pad and connecting portion are welded; And

The linearly inclination in the edge of pad, the inclination of this linearity is parallel with the scolding tin flow direction of scolding tin following current.

6. electronic installation according to claim 5 is characterized in that:

By the edge that makes above-mentioned pad is the concavo-convex above-mentioned inclination that forms.